Jazz, it has to be said, is a bit of a tart when it comes to other styles of music - it'll go off with any of them.
That's because it was created from the mixture of other forms, African blues and European classical just two of the traditions feeding in.
Jazz and the traditional folk music of these isles have "walked out" on numerous occasions, with varying levels of success.
Lammas was one group that achieved the synthesis. However, the most satisfying collaboration of the past decade has been that between f olk singer June Tabor and jazz pianist/accordionist Huw Warren.
Now, with saxophonist Iain Ballamy, they comprise the band Quercus (it means oak).
Making a short tour of England, they arrive at the mac on Monday for what should be a hugely enriching Birmingham Jazz gig.
June Tabor has slowly but consistently expanded her repertoire from pure English folk song out to popular songs from the past. At the same time her vocal style has expanded to bring a more jazzy flexibility to a genre which is often sung (rather too) straight.
Huw Warren is not only an improviser of great power, he is a masterful composer and, more importantly with Tabor, arranger. He has also increasingly looked to his Welsh background for inspiration.
Iain Ballamy is no stranger to collaborations outside jazz, and has done innovative work with Asian dance as well as looking folkwards with Scandinavian accordionist Stian Carstensen.
The intimacy of the venue should suit these musicians down to the ground.
High quality and absolute musical integrity is guaranteed, and that's why this mix of musics - English and Welsh folksong as well as original stuff - works so well: it is not contrived for marketability, but conceived from absolute logic.
Quercus play the mac on Monday at 8pm. Tickets are £10 available from 0121 440 3838.
* Another singer/group collaboration on Sunday evening at the Glee Club. The singer Liane Carroll joins Birmingham bassist Roger Innis and his band Erogerinniszone for this session.
Innis has an excellent album now in the shops and his band, with Chris Storr on trumpet, Carlton Romillie on sax and Jazz Jamaica's drummer Rod Youngs, has a contemporary funk jazz style ideally suited to the venue. This Birmingham Jazz event starts at 8.30pm, and tickets are £10 from the club's hotline 0870 241 5093 or at glee.co.uk
* Other good gigs this week: Tomorrow: Roots music from Ghana at the mac. Atongo Zimba plays the molo (a two-string cal-abash guitar) and is part of the Africa Acoustic series of gigs. Tickets are £9.25, again from 0121 440 3838.
Saturday: Mike Sanchez Rhythm & Blues Revue with special guests take over the Town Hall, Kidderminster. It starts at 8pm and tickets are £10 to £15. Tel: Wyre Forest District Council Events Section 01562 732979.
Saturday: Broken beats with style from West London's finest: Silhouette Brown, part of the All That Jazz series at The Drum. Doors open 9pm £10 (£8 concessions) £12 on the door. To book call 0121 333 2444 or go to the-drum.org.uk